The use of wing tip devices, such as winglets, on aircraft is well known. Such devices seek to improve the aerodynamic performance of the aircraft, typically reducing induced drag and increasing lift. It can be desirable to have relatively long wing tip devices, but the length of downwardly extending (anhedral) wing tip devices tends to be limited by airport operating rules which govern various clearances required when maneuvering around the airport (such as the span and/or ground clearance required for gate entry and safe taxiway usage). There has therefore tended to be a focus on using longer upwardly extending (dihedral) wing tip devices, than downwardly extending devices.